Bacteria, Archaea, And Viruses

Explanation
Archaea and Bacteria are prokaryotic systems because they lack a nucleus and other membrane-bound organelles. They are single-celled microorganisms that have a simple cellular structure and are typically smaller in size compared to eukaryotic organisms. Archaea and Bacteria are both classified as prokaryotes and are distinct from eukaryotes such as Protista, Fungi, Plantae, and Animalia, which have more complex cellular structures with a nucleus and other organelles.

Explanation
Binary fission: a form of cell division in which one cell pinches in two
Binary fission does NOT include mitosis

Explanation
Plasmids are small, circular DNA molecules that are separate from the chromosomal DNA. They are commonly found in bacteria and can replicate independently. Plasmids often carry genes that provide advantages to the bacteria, such as antibiotic resistance or the ability to produce certain proteins. Therefore, it is correct to say that small, circular DNA molecules are called plasmids.

Explanation
Bacteria may have a cell wall with unusual chemical properties, a slimy-coating capsule, and fimbriae, which are hair-like appendages. The cell wall provides structural support and protection for the bacteria, and the unusual chemical properties may help the bacteria adapt to different environments. The slimy-coating capsule helps the bacteria adhere to surfaces and protect against the immune system. Fimbriae are used for attachment to surfaces and other cells, allowing the bacteria to form biofilms or facilitate the transfer of genetic material.

Explanation
The statement is true because Kingdom Archaea, also known as archaebacteria, indeed has a unique RNA sequence and lacks muramic acid in their cell walls. The unique RNA sequence distinguishes them from other organisms, while the absence of muramic acid sets them apart from bacteria, which typically have cell walls containing this compound. These characteristics contribute to the distinctiveness and uniqueness of Kingdom Archaea.

Explanation
Methane bacteria is anaerobic because it can survive and thrive in environments with little to no oxygen. These bacteria are capable of producing methane gas through a process called methanogenesis, which occurs in oxygen-deprived conditions such as wetlands, swamps, and the digestive systems of animals. Methane bacteria play a crucial role in the carbon cycle by converting organic matter into methane, a potent greenhouse gas.

Explanation
Salt bacteria are able to carry out a simple form of photosynthesis using bacterial rhodopsin, a red pigment found in their membranes. This pigment helps them capture light energy and convert it into chemical energy, enabling them to produce their own food. This process is similar to the way plants and algae perform photosynthesis using chlorophyll. Therefore, the statement "Salt bacteria can carry on a simple form of photosynthesis with the aid of a membrane-bound red pigment called bacterial rhodopsin" is true.

Explanation
The statement is true because Kingdom Bacteria, also known as true bacteria, does contain muramic acid in the cell walls. Additionally, the RNA base sequences and lipids found in Kingdom Bacteria are different from those found in archaebacteria.

Explanation
Heterotrophs are organisms that obtain their energy by consuming organic matter from other organisms. Bacteria are a diverse group of microorganisms, and while there are some bacteria that are autotrophs (able to produce their own food through photosynthesis or chemosynthesis), the majority of bacteria are heterotrophs. They rely on external sources of organic matter to meet their energy needs. Therefore, it can be inferred that most bacteria are heterotrophs.

Explanation
NOT found in higher plants

Explanation
Cyanobacteria are photosynthetic organisms that have the ability to produce oxygen as a byproduct of their photosynthesis process. During photosynthesis, cyanobacteria use sunlight to convert carbon dioxide and water into glucose and oxygen. This process is similar to the photosynthesis carried out by plants. Therefore, it is true that cyanobacteria produce oxygen when they photosynthesize.

Explanation
Organisms that can fix nitrogen, such as certain bacteria, have the ability to convert atmospheric nitrogen into a form that can be used by other organisms. This process, known as nitrogen fixation, is important because nitrogen is an essential nutrient for living organisms. Additionally, during nitrogen fixation, these organisms release oxygen as a byproduct. Therefore, it is true that only organisms that can fix nitrogen use atmospheric nitrogen and produce oxygen.

Explanation
Heterocysts are larger, colorless cells that are involved in nitrogen fixation and often undergo fragmentation. Nitrogen fixation is the process by which nitrogen gas from the atmosphere is converted into a form that can be used by plants. Heterocysts are specialized cells found in certain types of cyanobacteria that have the ability to fix nitrogen. They are colorless because they lack chlorophyll, which is responsible for the green color in photosynthetic cells. Heterocysts also have the ability to undergo fragmentation, which allows for the dispersal of nitrogen-fixing cells to different areas.

Explanation
Akinetes are thick-walled cells that can resist freezing and other adverse conditions. These cells are formed by certain types of bacteria, such as cyanobacteria, as a survival strategy. When environmental conditions become unfavorable, the bacteria differentiate into akinetes, which have a thick cell wall that provides protection against freezing temperatures and other harsh conditions. Akinetes can remain dormant for extended periods and then germinate when conditions become favorable again. This adaptation allows the bacteria to survive and continue their growth and reproduction even in challenging environments.

Explanation
Viruses are composed of a nucleic acid core, either RNA or DNA, which contains the genetic information of the virus. This core is surrounded by a protein coat, also known as a capsid, which protects the genetic material. This structure is common to all viruses and is essential for their replication and infection of host cells. Therefore, the statement that viruses consist of a nucleic acid core surrounded by a protein coat is true.

Explanation
Viruses are parasitic entities that cannot reproduce on their own. Instead, they rely on host cells to replicate and produce more virus particles. Once inside a host cell, the virus uses the cellular machinery to replicate its genetic material and assemble new virus particles. This process ultimately leads to the destruction of the host cell and the release of newly formed viruses, which can go on to infect other cells. Therefore, it is true that viruses reproduce themselves only by taking over host cells.

Explanation
Tail fibers that stick to receptors is the initial step in the viral life cycle known as attachment. This process involves the tail fibers of a virus binding to specific receptors on the surface of a host cell. This attachment allows the virus to recognize and bind to the appropriate cell, facilitating the next steps in the infection process. Once attached, the virus can then penetrate the host cell, release its genetic material, undergo biosynthesis, and eventually mature to produce new viral particles.

Explanation
Penetration is the correct answer because the tail sheath of a bacteriophage is responsible for injecting the viral DNA into the host cell during the infection process. The tail sheath contracts, allowing the tail core to penetrate the host cell's membrane and deliver the viral genetic material. This step is crucial for the virus to take control of the host cell's machinery and replicate itself.

Explanation
Biosynthesis is the correct answer because it refers to the process in which viral DNA takes over the host cell's machinery to produce enzymes and proteins necessary for its own replication and structure. This step occurs after the viral DNA has entered the host cell and before maturation and release. During biosynthesis, the viral DNA makes enzymes that break down the host DNA and uses the nucleosides for its own replication. It also produces proteins that contribute to the structure of the virus.

Explanation
Maturation refers to the process in which viral proteins assemble. During this stage of the viral life cycle, individual viral proteins come together to form a complete viral particle. This assembly is crucial for the virus to become infectious and capable of infecting host cells. Once the viral proteins have successfully assembled, the virus is considered mature and ready for the next stages of the life cycle, such as attachment to host cells and penetration into them.

Explanation
Viral enzymes destroy the cell membrane and escape during the release phase of the viral life cycle. This is the final step in the viral replication process, where newly formed viral particles are released from the host cell to infect other cells. Once the cell membrane is destroyed by viral enzymes, the viral particles are able to exit the host cell and spread to other cells in the body.

Explanation
-Do not have capsids (protein coats)